1. Field of the Invention
This invention relates to an electrical connector shell, and in particular to a connector shell having an integrated backshell, front shield, and rear cable clamp so as to provide a continuous ground path between the front mating end of the shell and the cable shielding. The invention also relates to an electrical connector including an integrated stamped sheet metal backshell, D-shell front mating end, and rear cable clamp, a stamped metal top cover, and an injection molded insulator, and to a method of assembling such a connector.
2. Discussion of Related Art
The invention addresses the problem of ensuring shielding continuity at the connections between a cable of the type used in computing applications to carry high frequency data in order to prevent radiation leakage and provide all around protection from electromagnetic interference. The cables with which the present invention is concerned are the type which include multiple individual wires surrounded by a braided outer conductor, the outer conductor effectively shielding the individual wires of the cable. Connection of the cable is accomplished by terminating individual electrical connections to connector contacts surrounded by a metal shell, the metal shell being electrically connected at the rear to the braided outer conductor of the cable, and at the front to a shield that surrounds the connector contacts and establishes an electrical connection to the shell or housing of a mating connector or component.
Essentially, there are two areas in a conventional shielded cable connection where shielding continuity may be interrupted. The first is at the seam between the metal backshell which houses the cable termination and the front shield which surrounds the contacts and establishes electrical contact with the corresponding mating connector or component, and the second is at the interface between the cable clamp at the rear of the connector and the cable shield.
One solution to the problem of discontinuities at the seam between the metal shell and the front shield is disclosed in commonly assigned copending application Ser. No. 08/788,777, filed Jan. 24, 1997. The copending application teaches the concept of integrating the front shield and backshell by die casting the front shield together with the backshell to form a unitary structure. However, while the shielding continuity provided by this structure is superior to that provided by conventional connectors of the same general type, there are situations where stamped metal backshells are preferable to die cast backshells. As a result, the invention seeks to apply the concept of an integral front shield and cable clamp disclosed in the copending application to a stamped metal connector shell rather than a die cast connector shell. In addition, although the connector described in the copending application is relatively simple to assemble, the present invention further reduces and simplifies the steps necessary to assemble the connector.
The related problem of eliminating shielding discontinuities at the interface between the backshell and the rear cable clamp of the conventional connector has also been addressed in commonly assigned copending application Ser. No. 08/788,777. However, the context is again that of a die cast metal connector shell, in which cable gripping teeth can be cast directly into the passage through which the cable enters the rear of the backshell. Another die cast connector shell with integral cable gripping structures, but without an integral front shield, is also disclosed in U.S. Pat. No. 5,244,415.
In the case of stamped metal connectors, the most typical arrangement is that illustrated, by way of example, in U.S. Pat. No. 5,055,070, which discloses a connector shell made of a separate front shield, connector retaining backshell, and back shield/cable clamp, the connector shell being overmolded after assembly.
There are of course electrical connectors in which a mating front portion is integral with the rear portion of the connector, including cylindrical connectors, BNC connectors, and so forth. However, connectors of the type with which the present invention is concerned have consistently used a separate shield, as described in numerous patents, including the '415 patent and U.S. Pat. Nos. 4,678,256, 4,689,728, 4,786,260, 4,822,304, 44,854,890, 4,921,441, and 5,108,294, all of which disclose cable connectors having discrete or separate trapezoidal shield arrangements, rather than integral front shields, and which therefore cannot provide optimal electrical continuity between the outer conductor of the cable and the shield.
In summary, none of the prior connector arrangements suggests a cable connector of the type having both a stamped metal shell to which the outer braid of the cable is electrically connected and a front contact shield, which is capable of providing a continuous low resistance electrical ground path from the outer cable conductor all the way to the shield, with no seams and thus optimal electrical properties, and which eliminates the need for a dielectric contact support structure. In all of the prior connectors of the type with which the invention is concerned, the front shield is a discrete structure from the metal shell, and while a connector shell without any seams between the rear cable clamp and the front shield is disclosed in copending U.S. patent application Ser. No. 08/788,777, the connector shell of the copending application is a die cast metal shell rather than a stamped metal shell, and none of the other references listed above contains any teachings of suggests of providing similarly front shield to rear cable clamp continuity in a stamped metal connector shell.